College of Arts and Sciences

 

Natural Sciences
Quest Project

  • Research Project: Johanna Dolch; The Effect of Air Pollution of the Growth of Cladophora in the Great Lakes and the Viability of the Macroalgae as an Alternative Fuel Source; presenting at American Chemical Society Annual Meeting 2009; brief description: see Exhibit A.

 

Exhibit A: College of Arts and Sciences
Quest Project Description
The Effect of Air Pollution of the Growth of Cladophora in the Great Lakes and the Viability of the Macroalgae as an Alternative Fuel Source
Department of Chemistry, Lawrence Technological University
Johanna Dolch
Received May 11, 2009

The relationship between the amount of air pollution and the growth of a nuisance algae in the Great Lakes, Cladophora glomerata, was determined by obtaining wild samples of the algae and introducing a pollution gas mixture containing NOx, CO2 and CO in an air balance. Additionally, it was determined if Cladophora is a viable source of biodiesel. There was an increase in density for the algae that was fed the pollution mix when compared to the algae that was pollution free. After the introduction of the pollution gas mixture, the lipids were extracted using a modified Bligh-Dyer method that does not use chlorinated solvents. Both the organic and aqueous layers were analyzed for lipids via FT-IR. The lipid content of the algae was determined by searching for characteristic peaks for esters at 1750-1715 cm-1 for the C=O stretch and at 1300-1000 cm-1 for the C-O stretch. Based on the IR spectra for the samples obtained in the experiment, there were no observed esters in either of the layers. However, due to detection limits of the FT-IR instrument, a definitive conclusion cannot be made at this time in regard to the lipid content of the algae. Further analysis, including GC-MS analysis, is necessary to make a final determination of the possibility of Cladophora as an alternative fuel source.

Excessive algal blooms, usually resulting from eutrophification from pesticides and industrial waste, are an environmental and health hazard in the Great Lakes. Between the 1950s and 1970s, excessive growth of Cladophora was linked to higher levels of phosphates in the Great Lakes.  As a result, the reduction of phosphorus containing pollutants through regulations from the Great Lakes Water Quality Agreement appeared to solve the problem as a decline in Cladophora blooms was observed in the 1980s with the removal of phosphates from detergents, improved sewage waste disposal methods and alternative fertilizer sources in agriculture. 

Over the past decade, however, the Cladophora problem has re-emerged. Large mats of the algae wash up on the shores of the Great Lakes, particularly in Lake Michigan, and are not only an aesthetically unpleasing, but the mats are also health risks as they promote the growth of pathogens such as botulism. Additionally, increased Cladophora blooms result in a decrease in the quality of available drinking water for Great Lakes region residents.  Unfortunately, reasons for the recent resurgence of the nuisance algae remain unknown since phosphate levels in the Great Lakes are at a relatively low level. There has been some speculation that the increase in growth of the algae has resulted from the introduction of zebra mussels into the Great Lakes as the mussels increase water clarity, which promotes growth of the algae as more sunlight reaches the bottoms of the lakes. 

Algae, such as Cladophora, offer a unique source of alternative fuels. Since all green algae use photosynthesis to transform carbon dioxide and sunlight into energy, they are able to double their weight several times a day, which makes algae a particularly persistent pest in the Great Lakes. Additionally, microalgae can produce more oil per acre than any other plant that is currently being used for biodiesel. Algae is versatile in that it can it can grow in saltwater, freshwater and terrestrial environments, which makes it an ideal candidate for alternative fuels since it is not geographically isolated from areas that have an increased fuel demand. Additionally, because increased carbon dioxide pollution from anthropogenic sources has been linked to global warming, using algae as a way to sequester carbon dioxide is an excellent solution to the ever-growing global warming problem. Additionally, using the algae as a fuel source produces less carbon dioxide overall as the carbon footprint is reduced as the algae consumes a portion of the carbon dioxide from the atmosphere.

Much of the previous work on biodiesel from algae has been done on microalgae.  Macroalgae, such as Cladophora, has previously not been viewed as a viable source for biodiesel because it has been mainly used for food or other purposes.  Additionally, macroalgae does not possess as much oil as microalgae does and is more difficult to grow.  Because of these difficulties, the extraction of biodiesel from macroalgae has not received nearly as much attention as microalgae biodiesel extraction. 

Since Cladophora is such a nuisance algae in the Great Lakes, if a favorable amount of biodiesel can be extracted from it, it would not only help to clean up the shores of the Great Lakes, but also if the increase in Cladophora is attributed to air pollution, than it can be used as a way to help alleviate the pollution problem. In this study, a particular species of algae that is native to the Great Lakes, Cladophora glomerata, was grown under laboratory conditions and one sample was fed a pollution mix containing NOx, CO2, and CO, common air pollutants in the Mid-West, and the growth rate of the samples monitored before and after the addition of the pollutants to one of the samples. Finally, the samples were extracted and analyzed for lipids, particularly methyl esters, which are used to determine biodiesel quality, via FT-IR.

Results and Discussion

The relationship between the amount of algae growth and pollution has discovered throughout this experiment. The actual masses of the algae samples before and after addition of the pollutants were not taken since the algae was subcultured as quickly as possible so as to avoid shocking the samples into dormancy. However, it was observed that the algae sample that had NOx added to it became more dense than the sample that did not have NOx added to it. It can be inferred from this observation that the addition of the pollutants to the algae assisted its growth. The delay of the observed increase in green color between the algae in Flask A and its subculture was probably due to the act of subculturing, which probably placed a small delay in the growth cycle of the algae as its environment was disturbed. In future experimentation, it has been recommended that two subcultures be created and the same size flask as the original culture be used. In doing so, one of the subcultures can be kept as a control to see how the algae was affected by the act of subculturing while experiments can be performed on the other one.

Based on analysis of the FT-IR spectra, it would appear that there were no esters present. An ester would have been identified by an aliphatic C=O stretch from 1750 - 1735 cm-1, α,β- unsaturated C=O stretch from 1730 - 1715 cm-1 and C-O stretch from 1300-1000 cm-1. However, a definitive conclusion on the presence of esters in the algae cannot be made simply based on the IR spectra for the extracted samples as some of the lipids may still be contained in the sample matrix, most likely as a part of cells. There is still much research to be done before the viability of biodiesel from Cladophora can be verified or refuted. At this point, a better extraction method that will simplify the sample matrix is necessary as there are many interferences found in biological samples. Dr. Julie Zwiesler-Vollick has proposed several adaptations to the extraction method that may be necessary for future experimentation. Additionally, it should be noted that there appeared to be a significant amount of masking of the IR spectra of the extracted samples by the solvents as observed by the characteristic peaks for ethanol observed in the aqueous layers of the samples and cyclohexane in the organic layers of the samples. 

Additional avenues of analysis are also necessary in order to determine the feasibility of Cladophora as a biofuel. Once the sample matrices have been simplified, it would be prudent to perform GC-MS analysis of the extracted samples and compare the spectra to spectra for esters, such as 9-octadecenoic acid methyl ester, used for biodiesel. High biodiesel quality can be determined from the concentration of fatty acid methyl esters (FAMEs) in the biodiesel. Previous work by Xu with microalgae has found that oleic acid methyl ester as the most abundant FAME. The use of this and other esters as a standard for future GC-MS analysis would help to determine the biodiesel content of the algae.

Finally, it should be noted that in dealing with biodiesel extraction from macroalgae, there are many difficulties that are not normally seen with microalgae due to the increased complexity of the macroalgae when compared to the microalgae. Additionally, the sheer size of the macroalgae presents a problem as it may be necessary to literally have tons of macroalgae mass in order to extract a small sample of biodiesel since the organism is structurally dissimilar to microalgae. The lipid content of macroalgae may also be difficult to determine as it has been observed that some of the lipids maybe remain trapped within cell walls that are resistant to destruction. It is the integrity of the algae's cells that make it such a hardy pest within the Great Lakes.

In conclusion, the wide scope of this project was met by the constraints of time. This entire experiment could very well be enough for an entire doctoral thesis.  That being said and also taking into account the knowledge of a chemistry student that contains only novice biological knowledge, a significant of research as done, but there is still much, much more to do, which is both the blessing and curse of research.